Research of relationship between iris clarity and human eye shooting distance
虹膜清晰程度与人眼拍摄距离对应关系研究*

The existing iris reader usually requires human eye imaging in smaller depth of filed, many users become upset because of adjusting position repeatedly when acquisition the iris images. If the shooting range can be gave, it will be convenient for the use of users. Under the condition of the human eye deviating the focus of the camera,this paper studied and established the corresponding relationship between the iris image clarity and the shooting distance between the eye and lens, and evaluated by experiments the performance of four evaluation functions being used to describe the corresponding relationship between the image clarity and the eye shooting distance. Experimental results show that when the human eyes move in 90150 mm range, the iris image clarity firstly increases to maximum gradually, then reduces gradually; when the maximal shooting range between human eyes and camera is 106132 mm, the acquired iris image clarity will be enough for the performance of the iris recognition system, thus, the steady recognition effect can also be obtained.